The early warning of rock mass failure in deep hard-rock mines presents a significant challenge for mine safety management. Microseismic monitoring data offer a novel analytical approach to address this issue. This study investigates the evolutionary patterns of rock mass failure in mining areas through the analysis of spatiotemporal energy data from microseismic events. Initially, key spatiotemporal energy parameters are extracted to identify microseismic events associated with localized damage and their periodic characteristics. Subsequently, a spatiotemporal fractal dimension analysis method is established to achieve fractal interpretation of the data by integrating field cloud maps. Finally, an early warning model centered on temporal energy is constructed, which delineates warning zones through a comprehensive evaluation of fractal dimensions, thereby providing decision-making support for mine safety.

Deep coal seams in China are generally characterized by high geothermal temperatures and high in situ stresses. Their coupled effects can alter fracture seepage conditions and promote gas-lock retention, thereby impairing water-injection seepage. However, the microscopic gas-lock evolution and the comparative seepage responses of different surfactants under coupled temperature–stress conditions remain insufficiently understood. Therefore, an analytical fracture-permeability model incorporating temperature–stress effects derived based on the fracture cubic law and deformation superposition, and a microscale visualization platform integrating temperature regulation, mechanical loading, fluid displacement, and real-time observation were developed using a fracture-network glass micromodel. Deionized water, sodium dodecyl sulfate (SDS), Triton X-100 (TX-100), and dodecyl dimethyl benzyl ammonium chloride (DDBAC) were employed as displacement fluids under different temperature, confining-pressure, and flow-rate conditions. The evolution of gas-lock proportion, gas-lock number, seepage pressure differential, and equivalent fracture permeability was quantified, and the temperature–confining pressure model was fitted to the experimental data. The results showed the following: (1) as the temperature increased from 25 °C to 40 °C and the confining pressure increased from 1 MPa to 3 MPa, the gas-lock proportions of deionized water and SDS increased by 41.7% and 38.9%, respectively, while their equivalent fracture permeabilities decreased by 59.3% and 54.1%; (2) in comparison, TX-100 and DDBAC showed smaller increases in gas-lock proportion of 13.2% and 15.6%, accompanied by permeability decreases of 22.5% and 25.8%, respectively; (3) under otherwise identical conditions, increasing the flow rate from 0.1 to 0.3 mL min⁻¹ reduced the average gas-lock proportion by 17.4% and increased the equivalent fracture permeability by 23.9%, indicating enhanced liquid displacement and reduced gas-lock blockage; (4) TX-100 and DDBAC exhibited comparatively smaller variations in gas-lock retention and equivalent fracture permeability with increasing temperature and confining pressure, whereas SDS showed a stronger temperature-dependent response, which is associated with the combined effects of fluid properties, gas–liquid redistribution, and local interfacial trapping; and (5) the fitted models for the four injection media yielded coefficients of determination ($R^2$) greater than 0.92 and mean absolute percentage errors (MAPE) below 8%, demonstrating good internal fitting consistency within the present dataset rather than independent predictive capability. Based on controlled microscale visualization experiments, this study clarifies the relative gas-lock and seepage responses of different injection media under the investigated temperature–confining pressure conditions and provides an experimental and theoretical basis for further studies on surfactant-enhanced water injection in fractured coal.

Conventional standard oxygen-consumption-rate models can retain an apparent dependence on reactor height and gas flow rate when outlet oxygen concentrations become low. To examine this issue, programmed-temperature oxidation experiments were conducted using gas-fat coal from the Zhuxianzhuang Coal Mine. Two packed coal-bed configurations were used: a full bed (coal-bed height, 20 cm; packed-coal volume, 250 cm³) and a half bed (coal-bed height, 10 cm; packed-coal volume, 125 cm³); both were operated at inlet flow rates of 80, 100, and 120 mL min⁻¹. Outlet O₂, CO, and CO₂ samples were collected near the end of each isothermal hold and analysed by gas chromatography. An empirical effective oxygen-concentration correction parameter was introduced to revise the conventional standard oxygen-consumption-rate model, and corresponding standard CO and CO₂ generation-rate and calculated heat-release-intensity models were derived. The outlet oxygen concentration exhibited four apparent stages with increasing temperature: slow decrease, rapid decrease, renewed slow decrease, and stabilization. Above approximately 195 °C, the outlet oxygen concentration approached a nonzero plateau. On the basis of this plateau and the consistency of results obtained under the tested conditions, a value of 1.21 vol.% was selected as an empirical correction parameter for the present system. The conventional model produced increasingly separated oxygen-consumption-rate curves at high temperatures and yielded R² = 0.930. After introducing the correction parameter, the curves obtained under the tested conditions showed improved convergence and R² increased to 0.993. The revised standard CO and CO₂ generation rates and calculated heat-release intensities likewise showed reduced dependence on reactor height and flow rate within the present dataset and increased exponentially with temperature. These empirical correlations describe the tested coal under the specified reactor and heating conditions. Independent validation is required before extending them to other coals or operating conditions.